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[PATCH RESEND 1/12] fs: Add support FALLOC_FL_INSERT_RANGE for fallocate

To: david@xxxxxxxxxxxxx, tytso@xxxxxxx
Subject: [PATCH RESEND 1/12] fs: Add support FALLOC_FL_INSERT_RANGE for fallocate
From: Namjae Jeon <linkinjeon@xxxxxxxxx>
Date: Tue, 17 Feb 2015 00:47:48 +0900
Cc: linux-fsdevel@xxxxxxxxxxxxxxx, linux-kernel@xxxxxxxxxxxxxxx, linux-ext4@xxxxxxxxxxxxxxx, xfs@xxxxxxxxxxx, a.sangwan@xxxxxxxxxxx, bfoster@xxxxxxxxxx, mtk.manpages@xxxxxxxxx, linux-man@xxxxxxxxxxxxxxx, linux-api@xxxxxxxxxxxxxxx, Namjae Jeon <linkinjeon@xxxxxxxxx>, Namjae Jeon <namjae.jeon@xxxxxxxxxxx>
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From: Namjae Jeon <namjae.jeon@xxxxxxxxxxx>

FALLOC_FL_INSERT_RANGE command is the opposite command of
FALLOC_FL_COLLAPSE_RANGE that is needed for advertisers or someone who want to
add some data in the middle of file. FALLOC_FL_INSERT_RANGE will create space
for writing new data within a file after shifting extents to right as given
length. and this command also has same limitation as FALLOC_FL_COLLAPSE_RANGE,
that is block boundary and use ftruncate(2) for crosses EOF.

Signed-off-by: Namjae Jeon <namjae.jeon@xxxxxxxxxxx>
Signed-off-by: Ashish Sangwan <a.sangwan@xxxxxxxxxxx>
Cc: Brian Foster<bfoster@xxxxxxxxxx>
---
 fs/open.c                   |    8 +++++++-
 include/uapi/linux/falloc.h |   17 +++++++++++++++++
 2 files changed, 24 insertions(+), 1 deletion(-)

diff --git a/fs/open.c b/fs/open.c
index 813be03..762fb45 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -232,7 +232,8 @@ int vfs_fallocate(struct file *file, int mode, loff_t 
offset, loff_t len)
 
        /* Return error if mode is not supported */
        if (mode & ~(FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE |
-                    FALLOC_FL_COLLAPSE_RANGE | FALLOC_FL_ZERO_RANGE))
+                    FALLOC_FL_COLLAPSE_RANGE | FALLOC_FL_ZERO_RANGE |
+                    FALLOC_FL_INSERT_RANGE))
                return -EOPNOTSUPP;
 
        /* Punch hole and zero range are mutually exclusive */
@@ -250,6 +251,11 @@ int vfs_fallocate(struct file *file, int mode, loff_t 
offset, loff_t len)
            (mode & ~FALLOC_FL_COLLAPSE_RANGE))
                return -EINVAL;
 
+       /* Insert range should only be used exclusively. */
+       if ((mode & FALLOC_FL_INSERT_RANGE) &&
+           (mode & ~FALLOC_FL_INSERT_RANGE))
+               return -EINVAL;
+
        if (!(file->f_mode & FMODE_WRITE))
                return -EBADF;
 
diff --git a/include/uapi/linux/falloc.h b/include/uapi/linux/falloc.h
index d1197ae..3e445a7 100644
--- a/include/uapi/linux/falloc.h
+++ b/include/uapi/linux/falloc.h
@@ -41,4 +41,21 @@
  */
 #define FALLOC_FL_ZERO_RANGE           0x10
 
+/*
+ * FALLOC_FL_INSERT_RANGE is use to insert space within the file size without
+ * overwriting any existing data. The contents of the file beyond offset are
+ * shifted towards right by len bytes to create a hole.  As such, this
+ * operation will increase the size of the file by len bytes.
+ *
+ * Different filesystems may implement different limitations on the granularity
+ * of the operation. Most will limit operations to filesystem block size
+ * boundaries, but this boundary may be larger or smaller depending on
+ * the filesystem and/or the configuration of the filesystem or file.
+ *
+ * Attempting to insert space using this flag at OR beyond the end of
+ * the file is considered an illegal operation - just use ftruncate(2) or
+ * fallocate(2) with mode 0 for such type of operations.
+ */
+#define FALLOC_FL_INSERT_RANGE         0x20
+
 #endif /* _UAPI_FALLOC_H_ */
-- 
1.7.9.5

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